2000 Nissan Sentra P0171 Code: Recurring Lean Bank 1 Issue with Self-Clearing Behavior
I've been experiencing the P0171 diagnostic trouble code on my 2000 Nissan Sentra, which has appeared twice in the past few months. Despite no noticeable driveability issues—such as rough idling, stalling, or loss of power—I’ve seen this code come back repeatedly after clearing it at AutoZone. The most recent occurrence involved the check engine light turning on and then automatically turning off after three starts and shutdowns. This pattern has repeated twice now, with no recurrence in over two days. I've already cleaned the mass air flow (MAF) sensor and replaced the spark plugs with Bosch Platinum-type plugs—though I did not use the original NGK dual-tipped platinum plugs. After these changes, the code still reappeared when the car was driven for more than three weeks. My mechanic recently inspected the vehicle and found no active codes during a scan. He noted that the self-clearing behavior of the P0171 code is unusual and suggests an intermittent sensor failure—possibly in the oxygen sensors or exhaust system. He emphasized that if the MAF were faulty, I would likely experience a rough idle or stalling condition, which has not occurred. I’m now questioning whether this recurring issue is due to a vacuum leak, low fuel pressure, or a failing oxygen sensor. Given that the code clears itself after multiple starts and stops, it may indicate an intermittent signal from a sensor rather than a persistent system failure. I’d like to know if further diagnostics—such as fuel pressure testing or vacuum leak checks—are recommended even when no codes are present.
What engine size does your 2000 Sentra have? Vacuum leaks are a common cause of P0171 and should be ruled out first.